Our research program continues to be directed in the following areas: 1. A study of the biliary excretion of estriol and other estrogens in various animals, particularly mammalian, in an attempt to ascertain the nature of the conjugates excreted in the bile. 2. The role of the kidney in the metabolism of steroids in the human, with particular emphasis on estrogens. A special study will be directed toward the localization of the enzymes responsible for conjugation of the estrogens and an attempt to define the kinetics of the enzymes. 3. The localization of estrogens in the pancreas and prostate has been established in our laboratory and studies will be directed toward elucidation of the intracellular proteins responsible for this localization. 4. Further studies on the nature of the binding of estrogen conjugates to plasma proteins.